JP2009526979A - Gauge for checking the radial dimensions of machine parts - Google Patents

Abstract

A gauge (1) for checking radial dimensions of a workpiece (60), e.g. the diameter of a crankpin orbitally rotating during grinding operations, includes a casing, a V-shaped reference device (4) and a rod that can move within the casing (2) with respect to the reference device, an end of the rod projecting from the casing and carrying a feeler (20) for touching the surface of the workpiece to be checked and transmitting the movements of the feeler to a transducer (22). A sealing system for preventing coolant, dust or other foreign matter from getting inside the casing includes a pneumatic conduit (6) for allowing compressed air to be blown from inside the casing to outside, and an internal seal that—in the non-operative condition—seals the opening through which the rod projects from the casing. According to an advantageous embodiment, the seal is fastened into a bushing guiding the rod and cooperates with a surface of the rod in order to get the tightness.

Description

  The present invention is a gauge for checking the radial dimension of a workpiece, characterized by a cylindrical surface, which is connected to the casing and to the casing and cooperates with the cylindrical surface of the workpiece. A shape reference device, a feeler that is in contact with the cylindrical surface of the workpiece and is adapted to move substantially linearly, a transfer element that is movably disposed in the casing and supports the feeler, and a V-shape reference device And a gage including a transducer including a movable element coupled to the transmission element and a seal system between the transmission element and the casing.

  Gauges having the characteristics described above are known in the art. An example is shown in an international patent application issued with the number WO-A-9712724, which determines the crankpin diameter during the orbital movement of the crankpin about a geometric axis. It refers to a specific device for checking. The gauge (which is part of the device and shown in FIGS. 6 and 7 of the international application) includes a V-shaped reference device that rests on the pin to be checked and a tubular guide casing. A transmission rod translates axially in the guide casing and supports a feeler that contacts the surface of the crankpin to be checked. The movement of the rod is detected by a measuring device having an inductive transducer including a first part integral with the tubular casing and a second part integral with the transmission rod and movable with the transmission rod.

  In the particular application shown in the aforementioned international patent application for checking a crankshaft machined on a grinding machine, it includes a fixed part of a gauge (including a tubular casing, a V-shaped reference device and a part of an inductive transducer) ) Is coupled to a support system that allows the entire gauge to perform the movement required to maintain contact with the pin to be checked while orbiting.

  The tubular casing has an opening through which the end of the transmission rod that supports the feeler projects. The sealing device closes such openings, thereby preventing the cooling medium and other foreign objects present in the work environment from entering the casing. More specifically, the sealing device is formed of a metal bellows whose end portions are fixed to the rod and the casing, respectively, and also has a function of preventing shaft rotation between the rod and the casing. To prevent improper angular position.

  Alternatively, known gauges include tubular outer gaskets of different shapes and / or materials that are formed, for example, from rubber and between the casing and the movable element that supports the feeler. Be placed. These gaskets provide a sealing action but do not play a substantial role as long as anti-rotation is involved.

  The increasing demand for internal combustion engines that characterizes maximum compaction results in the production of components with increasingly smaller dimensions. One such component is a crankshaft that requires a very accurate dimensional check.

  It may be difficult or impossible to use the device shown in the above cited patent publication WO-A-9712724 to check the crankshaft, characterized by very small nominal dimensions. For example, if the crankpin to be checked has a very small length, the result is the thickness of the V-shaped reference device, the corresponding ends of the feeler, rod and casing, and the part of the gauge that contains the sealing system Need to be small. In fact, such part of the gauge must be in contact with or very close to the surface of the pin during the checking operation, i.e. opposite cheek walls at the end of the pin Must be in between. It is particularly troublesome to reduce the size of the sealing system when the available play is for example less than 8-10 mm. In fact, to obtain a metal bellows or a different tubular gasket that features the right lateral size, a secure connection to both parts that can move relative to each other, and the right properties to ensure the required features for compliance and tightness Is troublesome.

  The object of the present invention is to characterize the small overall dimensions while ensuring excellent performance in checking the radial dimensions of machine parts, so that known gauge problems in applications where play of the parts to be checked is limited Is to provide a gauge to overcome the problem.

  This object is achieved by the gauge described above in which the sealing system includes an air line through which compressed air is blown from the inside to the outside of the casing.

  In the gauge according to the invention, the outer tubular gasket or the metal bellows can be omitted, so that by appropriately dimensioning the other components, even if the access means has a very small dimension, the checking operation is performed. Can be done. A typical application is to check for orbitable crank pins with limited axial dimensions, and for component dimensions where the pin dimensions and / or other mechanical parts of the application have a lateral size greater than 8-10 mm. It is an already described application that prevents its use.

  Certain embodiments of the invention also feature an internal seal that is substantially fixed to the casing or transmission rod, and ensures very good tightness against foreign objects even when the gauge is inactive. be able to. In this embodiment, since it is not necessary for air to continue to flow in the non-operating state, the consumption of compressed air can be positively limited.

  The present invention will now be described in detail with reference to preferred embodiments illustrated in the accompanying drawings, which are to be regarded as illustrative and not restrictive.

  The figure shows a gauge 1 according to the invention for checking the radial dimensions of machine parts, more specifically a so-called “snap gauge”. The gauge 1 is a V-shape that is adjustably coupled to the end of the casing 2 by means of a casing 2 having a long and narrow shape and a screw, for example schematically shown in FIG. A support system with a reference device 4 is included. The V-shaped reference device 4 includes two contact surfaces that are angled and are adapted to rest on the surface of the workpiece to be checked. The casing 2 has a through shaft hole 6. In this through shaft hole 6, the rod 8 is accommodated and the rod 8 is guided by a guide device having a first bush 12 and a second bush 14. Can be moved in the longitudinal direction. One end portion 10 of the rod 8 has a reduced diameter, protrudes from the casing 2 at the end portion of the shaft hole 6 and communicates with the V-shaped reference device 4. The axial hole 6 forms an enlarged region 7 characterized by cross sections having different diameter dimensions towards the opposite end. As will be described later, a feeler 20 that is in contact with the surface of the workpiece to be checked and moves in a substantially linear manner is fixed to the end 10 of the rod 8 and the inductive transducer 22 is movable. An element or core 23 is coupled to the opposite end of the rod 8 via the stem 21. The transducer 22 also includes a fixed part 24 which has a winding which is coupled to the casing 2 in the aforementioned enlarged region 7 of the shaft hole 6 and in which the core 23 can be translated. The windings (not shown in FIG. 1) are coupled via the electrical wiring of cable 26 to a known type of processing and display unit schematically shown in FIG. The

  The rod 8 is a transmission element that transmits to the core 23 of the transducer 22 the substantially linear movement of the feeler 20 (movement resulting from contact with the surface of the workpiece to be checked).

  In the example of FIG. 1, the thrust device acts on the flange 29 fixed to the rod 8 and pushes the end 10 supporting the feeler 20 outward, thereby causing the rod 8 and the surface of the enlarged region 7 of the shaft hole 6 to A compression spring 28 for applying axial thrust is included.

  The second bushing 14 arranged in the vicinity of the V-shaped reference device 4 and shown in more detail in FIGS. 4, 5 and 6 has a guide part 13 for guiding the longitudinal translation of the rod 8 and a wider diameter dimension. And an enlarged portion 15 having an inner surface, and a circular cavity 16 is formed in the enlarged portion. The sealing element includes an annular inner seal 18, for example a so-called “O-ring”, which is coupled to the casing 2, more specifically the annular inner seal is partly within the circular cavity 16 of the second bushing 14. Are housed.

  The annular seal 18 projects from the inner surface of the second bush 14 and cooperates with the mating surface of the rod 8 in the vicinity of the coupling region 9 of the rod 8 adjacent to the end 10 where the diameter dimension is reduced.

  The guide part 13 includes three further holes, more specifically longitudinal cuts 17, spaced from each other at an angular interval of 120 degrees to allow compressed air to flow.

  The anti-rotation device having the metal bellows 30 has an end fixed to the rod 8 and the casing 2, and is accommodated in the enlarged region 7 of the shaft hole 6. The metal bellows 30 only serves to substantially prevent mutual axial rotation between the rod 8 and the casing 2.

  A compressed air source schematically shown in the drawing and indicated by reference numeral 40 is coupled via a hose 42 to a side through hole 44 in the casing 2 that communicates the enlarged region 7 of the shaft hole 6 with the outside. Within the casing 2 there is a transverse hole 46 (which can be seen in FIGS. 2 and 3) of the shaft hole 6 between the enlarged region 7 described above and the first bush 12 and the second bush 14. It is formed between the intermediate region. Therefore, a part of the transverse hole 46 and the shaft hole 6 is an air conduit for allowing the compressed air supplied by the compressed air source 40 to pass in the casing 2 and toward the opening of the V-shaped reference device 4. Form. Compressed air can be discharged from the inside of the casing 2 to the outside through the air duct.

  The snap cage 1 uses, for example, a movable structure similar to the movable structure described and shown in the above mentioned patent publication WO-A-9712724 and which is an application part for checking the orbiting crankpin. Can be secured to an external support schematically shown in FIG.

  In the non-actuated state, the rod 8 is arranged at the position shown in FIGS. 1 and 5 under the thrust of the spring 28. Such a position is defined by a known, not shown limiting device that includes mechanical abutments that are pressed together by the thrust of the spring 28. In the vicinity of the coupling area 9, the mating surface of the rod 8 is pressed against the annular seal 18, so that the sealing of the gauge 1 is ensured. That is, the hole 6 is closed and no fluid or other foreign matter can approach the interior of the casing 2 at all.

  In order to perform the checking operation, the gauge 1 is manually or automatically connected to the workpiece 60 to be checked located between the cheeks 62, for example the cylindrical surface of the crank pin of the crankshaft 66 shown partially and schematically in FIG. Touched. The V-shape reference device 4 is in contact with the surface of the workpiece (FIG. 6) and, according to the example given, contacted such a surface during the orbital rotation of the workpiece 60, for example by the action of gravity. Keep the state (in this regard, see the description of the above-mentioned patent publication WO-A-9712724).

  A thrust against the thrust of the spring 28 is applied to the feeler 20 and the resulting movement of the feeler 20 is transmitted by the rod 8 to the core 23 of the transducer 22. The transducer provides a signal indicating the position of the feeler 20 relative to the V-shaped reference device 4 to the processing and display unit 25 that processes the signal and also provides an indication regarding the dimensions of the workpiece 60. When the gauge is applied in an “inter-process” check on a tool (more specifically, a grinder), such an indication can be used to control the grinding operation of the crankshaft 66.

  The compressed air supplied by the compressed air source 40 and blown into the casing 2 through the side hole 44 is formed by the air pipe formed by the transverse hole 46, the gap of the axial hole 6, the longitudinal cut 17, and the second It passes through the casing 2 in the longitudinal direction at the enlarged portion 15 of the bush 14. After contact between the feeler 20 and the surface of the workpiece 60, air can exit to the outside as the mating surface of the rod 8 moves away from the seal 18. The compressed air that flows to the outside blows out and prevents foreign matter (possibly in the vicinity of the contact area between the feeler 20 and the workpiece 60) from entering the casing 2, so that a sealing system is achieved. Is done. Airtightness is particularly important in “inter-process” applications where the part to be machined is covered by the cooling medium, and once the cooling medium enters the casing 2, the cooling medium adversely affects the function of the gauge 1. And may damage the components, among them the transducer 22.

  When the gauge 1 is moved away from the workpiece 60, the spring 28 pushes back the mating surface of the rod 8 to contact the seal 18, so that the hole 6 is sealed. As a result, air coming from the compressed air source 40 remains in the casing 2 under pressure. In this way, air consumption is advantageously limited to these check stages as the feeler 20 moves. Alternatively, the supply of compressed air can be interrupted in the inactive state.

  The gauge 1 according to the present invention ensures excellent hermeticity without an external sealing device such as a rubber or metal tubular gasket that cannot have a very small size to ensure the required performance. be able to. Since the external gasket can be omitted, a gage having a very small lateral dimension can be obtained for the parts that will be engaged with the workpiece to be checked. As a result, it is characterized by limited accessibility, such as a crankpin, whose longitudinal extent is defined by two mechanical parts that are very close to each other (eg 8-10 mm) as schematically shown in FIG. And can be used for checking parts.

  The internal seal 18 also ensures hermeticity when the gauge 1 is in an inoperative state when the gauge 1 is in a retracted position relative to the part to be checked or when it is stored, for example, in a storage magazine. In practice, the non-actuated state is not very important, but it is necessary to significantly increase the consumption of compressed air in order to prevent dust or other foreign matter from accumulating on the inlet of the casing 2 and entering inside. is there. The inner seal 18 can hold the compressed air in the casing 2 and / or can interrupt the production of air when the gauge 1 should not perform any checking operation, Does not impair proper sealing.

  The gauge according to the invention can characterize different embodiments with respect to what has been illustrated above.

  The hermeticity at the second bushing 14 can be done in different ways, for example, when a seal 18 or a similar functioning element is coupled to an appropriate region of the rod 8 and moves with that region. On the other hand, the inner surface of the bushing 14 is suitably formed to define a mating surface that is compatible with the seal and seals in the non-actuated state of the gauge 1.

  The thrust device can also have different embodiments and can include mechanisms having different shapes and arrangements, for example with magnetic elements.

  Instead of the first bushing 12, the guide device can include other guiding elements, for example ball bushings, or a suitably dimensioned single element, for example approximately corresponding to the second bushing 14. Can be included.

  Also, embodiments of the present invention may differ with respect to the arrangement of the rod 8 in the translational direction relative to the angle formed by the contact surface of the V-shaped reference device 4. More specifically, the translation direction of the rod 8 that supports the feeler 20 may be substantially aligned along the above-mentioned angle bisector, or may be slightly inclined with respect to the bisector. Also good.

  Also, the inductive transducer 22 may be replaced with an axial gauge head having a movable part that contacts the end face of the rod 8 substantially as shown in FIGS. 6 and 7 of the above-mentioned patent publication WO-A-9712724. it can. Other known types of transducers can be used (eg, light converters). In any case, it is beneficial to use a pneumatic device for airtightness that is independent of the circuit for detecting movement of the feeler 20. By keeping the two circuits independent of each other, on the one hand, the transducer can be selected based on the specific application involved to obtain the best metering performance, and on the other hand, the air described above in a very simple and inexpensive manner. A sealing circuit can be obtained. In practice, this air circuit does not require, for example, a stabilizer to control the pressure value, but rather can use air that is generally available for other work in the workplace environment (“factory air”). .

  Also, the gauge according to the invention can be fixed to different types of external supports, or can be used manually, for example, as a stand-alone device.

1 is a longitudinal cross-sectional view of a gauge according to a preferred embodiment of the present invention in which some elements are not cross-sectioned. It is a cross-sectional view of the gauge of FIG. 1 along the II-II line of FIG. FIG. 3 is a fragmentary longitudinal cross-sectional view of the gauge of FIGS. 1 and 2 along the line III-III of FIG. 2. It is a cross-sectional view of the gauge of FIG. 1 along the IV-IV line of FIG. FIG. 2 is an enlarged longitudinal cross-sectional view of a detail of the gauge of FIG. 1 in a non-actuated position with some components simplified for clarity. FIG. 2 is an enlarged longitudinal cross-sectional view of a detail of the gauge of FIG. 1 in an operating position with some components simplified for clarity. FIG. 2 is a side view of the gauge of FIG. 1 with several details sectioned during a crankpin crankpin check.

Claims (15)

A gauge (1) for checking the radial dimension of a workpiece (60), characterized by a cylindrical surface,
A casing (2),
A V-shaped reference device (4) coupled to the casing (2) and adapted to cooperate with the cylindrical surface of the workpiece (60);
A feeler (20) in contact with the cylindrical surface of the workpiece (60) and adapted to move substantially linearly;
A transmission element (8) arranged movably in the casing (2) and supporting the feeler (20);
A transducer comprising a movable element (23) adapted to supply a signal indicating the position of the feeler (20) relative to the V-shaped reference device (4) and coupled to the transmission element (8) 22)
A sealing system (18, 40-46) between the transmission element (8) and the casing (2);
In gauge (1) containing
Gauge (1), characterized in that the sealing system comprises an air line (6, 42-46) through which compressed air blows from the inside of the casing (2) to the outside.   The sealing system (18, 40-46) is coupled to one of the casing (2) and the transmission element (8) and the other of the casing (2) and the transmission element (8). The gauge according to claim 1, comprising a sealing element (18) adapted to cooperate with a mating surface.   Including a thrust device (28) adapted to apply axial thrust to the transmission element (8), the axial thrust maintaining mutual contact between the sealing element (18) and the mating surface The gauge according to claim 2, which is configured as described above.   The gauge according to claim 3, wherein the thrust device comprises a spring (28) arranged between the casing (2) and the transmission element (8).   The transmission element includes a rod (8), the casing (2) forms a shaft hole (6), the rod (8) is accommodated in the shaft hole (6) and is movable in an axial direction. Item 5. The gauge according to any one of Items 2 to 4.   The gauge according to claim 5, wherein the air line comprises at least a part of the shaft hole (6).   A guide device (12, 14) adapted to guide the translation movement of the rod (8) along the translation direction in the shaft hole (6), the guide device comprising the V-shaped reference device ( The at least bushing (14) coupled to the casing (2) in the vicinity of 4), the air line comprising a hole (17) in the at least one bushing (14). The gauge described.   The at least one bushing (14) defines an inner surface (13, 15), the sealing element (18) is coupled to the inner surface (13, 15), and the rod (8) defines the mating surface; The gauge according to claim 7.   The V-shaped reference device (4) defines a contact surface having a predetermined angle, and the translational direction of the rod (8) is arranged substantially aligned along a bisector of the angle. The gauge according to 7 or 8.   10. Gauge according to any one of claims 2 to 9, wherein the sealing element comprises an annular seal (18).   11. Gauge according to any one of the preceding claims, wherein the transducer (22) comprises a stationary part (24) coupled to the casing (2).   12. Gauge according to claim 11, wherein the transducer (22) is an inductive transducer.   13. An anti-rotation device comprising a metal bellows (30) housed in the casing (2) and fixed to the transmission element (8) and the casing (2). Gauge as described in the section.   The machine work piece (60) is orbiting during a check operation, and the V-shaped reference device (4) keeps in contact with the cylindrical surface of the work piece (60). Use of the gauge according to any one of the items.   Use of a gauge according to claim 14, for checking a crankpin (60) of a crankshaft (66) during a grinding operation with a tool.

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